本美国国家标准描述了噪声识别和噪声消除麦克风性能的测量程序。在漫反射噪声场中，以1/3倍频带间隔测量所需测试源的信噪比。麦克风的噪声消除性能定义为噪声消除指数（NCI），即信噪比的加权总和。被测麦克风的NCI可与所需的基线NCI进行比较 实验室标准压力传声器。

This American National standard describes procedures for measuring the performance of noise discriminating and noise canceling microphones. The signal-to-noise ratio is measured at 1/3 octave band intervals with the desired test source in a diffuse noise field. The noise canceling performance of the microphone is defined as the noise canceling index (NCI), a weighted summation of the signal-to-noise ratios. The NCI of the microphone under test can be compared to the required baseline NCI of a laboratory standard pressure microphone.